Statistical Characterization of UWB channel in Office Environments

In this paper, we present the statistical characterization of ultra wideband (UWB) channel of office environments in frequency domain. The 23,000 channel transfer functions of 46 transmitter-receiver location pairs are obtained using the measurement system based on frequency sweep technique. From the measured data, path loss exponent variation to the sub-frequency band is firstly reported. Then, distributions of received signals are analyzed considering the propagation environments and existence of line-of-sight (LOS). Finally, the statistical properties of received signal powers of frequency tones are reported. For LOS cases, as the separation between transmitter and receiver increases, the standard deviation of signal powers of the received frequency tones increases and probability, the received signal powers are located within specific range from the received power mean values, decreases

Empirical Ultra Wide Band Channel Model for Short Range Outdoor Environments

Abstract — This paper reports the empirical Ultra Wide Band (UWB) channel model for short range outdoor environments. The measurements were performed based on the frequency sweep method in frequency domain at two different parking lot environments. From the measured channel transfer functions, parameters of log-distance path loss law and the effect of frequency to the path loss exponent are extracted. The distribution of received signal is analyzed to the existence of line-of-sight (LOS) path also. For the characterization of frequency dependent UWB channel parameters, standard deviation and correlation properties of channel gain in frequency domain are analyzed. The standard deviation increases with transmitter-receiver separation in LOS condition and the correlation is regressed to the double-slope model

Statistical Characterization of UWB channel in Office Environments

본 논문에는 초광대역 통신시스템을 위한 주파수 영역의 통계학적 채널 모델을 서술하고 있다. 채널 모델링은 3개의 사무실 환경, 46개의 송, 수신 위치에서 얻어진 23,000개의 채널응답함수로 부터 얻어졌다. 측정실험을 통해 얻어진 데이터를 바탕으로 주파수 변화에 따른 경로감쇄지수 변화에 대해 서술한 후 전파환경과 가시경로의 존재여부에 따른 수신신호의 확률분포모델을 연구하였다. 마지막으로는 수신된 주파수 톤에 해당하는 수신파워의 표준편차와 같은 통계적 특성들을 고찰하였는데, 가시경로가 존재하는 경우에는 송, 수신기 사이의 거리가 멀어지면서 표준편차 값이 커지고 그에 따라 수신 주파수 톤의 파워가 평균 수신파워에서 일정한 범위 안에 들어올 확률이 떨어지는 것을 알 수 있었다.이 논문은 두뇌한국 21 사업과 대학 IT 연구센터 사업(ITRC)의 지원으로 수행되었다

Empirical Ultra Wide Band Path Loss Model in Office Environments

This paper reports the empirical path loss model of Ultra Wide Band (UWB) communications in office environments. The channel transfer functions of 46 transmitter-receiver location pairs are acquired using channel measurement system based on frequency sweep method. From the measured data, parameters of log-distance path loss formula are extracted considering propagation environments and existence of a line of sight path. The effect of frequency to the path loss properties of ultra wideband signal is presented also. Finally, statistical properties of received signal power with respect to the receiver conditions are analyzed

Signal optimization for UWB radio systems

Abstract This paper presents and studies three frequency-domain models for optimizing source pulses and detection templates in ultra-wideband radio systems. The optimization aims mainly at maximizing the EIRP band efficiency in the free space and the output of correlation detection at a receiver. These models are based on the Differential Evolution, an improved version of the Genetic Algorithm, and carried out on a set of UWB signals with given mathematical forms. As examples, these models are used to optimize the UWB signals for both narrowband thin-wire and wideband planar antenna systems. In addition, the optimized results are validated by non-optimization simulation

Sub-optimal Ultra-wide Band Receivers

Ultra-wide Band (UWB) has sparked a lot of interest lately from the industry and academia. The growing capacity of the wireless industry is requires a new communication system that satisfies the high data rate which does not interfere with existing RF systems. UWB promises to be this new technology. UWB also promises low power, low cost and flexibility. The UWB Channel opens up a huge new wireless channel with Giga Hertz Capacities as well as the highest spatial capacities measured in bits per hertz per square meter. When properly implemented UWB channel can share spectrum with traditional radio systems without causing harmful interference. In this thesis we studied and compared several reduced complexity sub-optimal Ultra-Wide Band receivers. These receivers include auto correlation receiver, the square value detector and the absolute value detector are studied. We consider OOK and PPM modulation schemes. We examine these schemes and the receivers on Gaussian and UWB indoor channels. We compare the performance with optimal receivers. A transmitter receiver system using 0.1us pulses implemented using existing hardware. A packet consisting of 24 bits were transmitted and the received signal could be verified in real time using a vector signal analyzer. The results show sub-optimal receivers provide a better trade off between robust, complexity and performance

Impacto dos canais não lineares em sistemas UWB

Mestrado em Engenharia Electrónica e TelecomunicaçõesEsta dissertação tem como principal objectivo o estudo da tecnologia Ultra Wideband (UWB). Serão também apresentadas propostas para arquitecturas de transmissores e receptores, baseados na comunicação por pulsos e verificação do impacto, que canais de transmissão nãolineares provocam nas arquitecturas propostas.The main purpose of this MSc thesis is the study of the Ultra Wideband (UWB) technology. Will be also proposed transceiver architectures, based on pulsed communications. The impact of non-linear channels in the quality of communication will be verified

Ultra-wideband Orthogonal Frequency Coded Saw Correlators

Ultra-wideband (UWB) communication new technology with ability to share the FCC allocated frequency spectrum, large channel capacity and data rate, simple transceiver architecture and high performance in noisy environments. Such communication advantages have paved the way for emerging wireless technologies such as wireless high definition video streaming, wireless sensor networks and more. This thesis examines orthogonal frequency coded surface acoustic wave (SAW) correlators for use in advanced UWB communication systems. Orthogonal frequency coding (OFC) and pseudo-noise (PN) coding provides a means for UWB spreading of data. The use of OFC spectrally spreads a PN sequence beyond that of CDMA because of the increased bandwidth; allowing for improved correlation gain. The transceiver approach is still very similar to that of the CDMA approach but provides greater code diversity. Use of SAW correlators eliminates many of the costly components that are needed in the IF block in the transmitter and receiver, and reduces much of the signal processing requirements. The OFC SAW correlator device consists of a dispersive OFC transducer and a wideband output transducer. The dispersive filter was designed using seven contiguous chip frequencies within the transducer. Each chip is weighted in the transducer to account for the varying conductance of the chips and to compensate for the output transducer apodization. Experimental correlator results of an OFC SAW correlation filter are presented. The dispersive filter is designed using seven contiguous chip frequencies within the transducer. SAW correlators with fractional bandwidth of approximately 29% were fabricated on lithium niobate (LiNbO3) having a center frequency of 250 MHz and the filter has a processing gain of 49. A coupling of modes (COM) model is used to predict the experimental SAW filter response. Discussion of the filter design, analysis and measurements are presented. Results are shown for operation in a matched filter correlator for use in an UWB communication system and compared to predictions

Ultra-wideband Spread Spectrum Communications using Software Defined Radio and Surface Acoustic Wave Correlators

Ultra-wideband (UWB) communication technology offers inherent advantages such as the ability to coexist with previously allocated Federal Communications Commission (FCC) frequencies, simple transceiver architecture, and high performance in noisy environments. Spread spectrum techniques offer additional improvements beyond the conventional pulse-based UWB communications. This dissertation implements a multiple-access UWB communication system using a surface acoustic wave (SAW) correlator receiver with orthogonal frequency coding and software defined radio (SDR) base station transmitter. Orthogonal frequency coding (OFC) and pseudorandom noise (PN) coding provide a means for spreading of the UWB data. The use of orthogonal frequency coding (OFC) increases the correlator processing gain (PG) beyond that of code division multiple access (CDMA); providing added code diversity, improved pulse ambiguity, and superior performance in noisy environments. Use of SAW correlators reduces the complexity and power requirements of the receiver architecture by eliminating many of the components needed and reducing the signal processing and timing requirements necessary for digital matched filtering of the complex spreading signal. The OFC receiver correlator code sequence is hard-coded in the device due to the physical SAW implementation. The use of modern SDR forms a dynamic base station architecture which is able to programmatically generate a digitally modulated transmit signal. An embedded Xilinx Zynq ™ system on chip (SoC) technology was used to implement the SDR system; taking advantage of recent advances in digital-to-analog converter (DAC) sampling rates. SDR waveform samples are generated in baseband in-phase and quadrature (I & Q) pairs and upconverted to a 491.52 MHz operational frequency. The development of the OFC SAW correlator ultimately used in the receiver is presented along with a variety of advanced SAW correlator device embodiments. Each SAW correlator device was fabricated on lithium niobate (LiNbO3) with fractional bandwidths in excess of 20%. The SAW correlator device presented for use in system was implemented with a center frequency of 491.52 MHz; matching SDR transmit frequency. Parasitic electromagnetic feedthrough becomes problematic in the packaged SAW correlator after packaging and fixturing due to the wide bandwidths and high operational frequency. The techniques for reduction of parasitic feedthrough are discussed with before and after results showing approximately 10:1 improvement. Correlation and demodulation results are presented using the SAW correlator receiver under operation in an UWB communication system. Bipolar phase shift keying (BPSK) techniques demonstrate OFC modulation and demodulation for a test binary bit sequence. Matched OFC code reception is compared to a mismatched, or cross-correlated, sequence after correlation and demodulation. Finally, the signal-to-noise power ratio (SNR) performance results for the SAW correlator under corruption of a wideband noise source are presented

ALLOCATION CONJOINTE DES CANAUX DE FREQUENCE ET DES CRENEAUX DE TEMPS ET ROUTAGE AVEC QdS DANS LES RESEAUX DE CAPTEURS SANS FIL DENSES ET ETENDUS

The general context of the present memory is about the cross-layer optimization of wire- less sensors networks based on ultra wide band technology UWB. The proposed solutions en- sure the share and the efficient allocation of spectral and temporal resources, the optimization of the energy consumption and the support of multi-constraints quality of services QoS. The most challenging issue is providing a tradeoff between the resource efficiency and the multi- constrained QoS support. For this purpose, we proposed a new Wireless Hospital Sensor Net- work (WHSN) three-tiered architecture in order to support large-scale deployment and to im- prove the network performance. Then we designed a channel allocation scheme (UWBCAS,) and a prioritized multi-channel multi-time slot MAC protocol (PMCMTP) to enhance network performance and maximize the resource utilization. Finally, we proposed a joint duty cycle scheduling, resource allocation and multi-constrained QoS routing algorithm (JSAR) which simultaneously combines, a duty cycle scheduling scheme for energy saving, a resource al- location scheme for efficient use of frequency channels and time slots, and an heuristic for multi-constrained routing protocol.Le thème général du sujet tourne autour de l’optimisation inter-couche des réseaux de cap- teurs basés sur la technologie ultra large bande ULB (UWB, Ultra Wide Band) moyennant des solutions protocolaires permettant d’un côté de répondre au besoin de qualité de service QdS à critères multiples dans les réseaux de capteurs sans fil et d’autre côté d’assurer le partage et l’alllocation efficace les ressources disponibles (spectrale et temporelle) ainsi que l’optimisation de la consommation d’énergie dans des tels réseaux. Le domaine d’application cible choisi dans le présent travail est les systèmes de suivi des patients au sein d’un réseau de capteurs déployé en hôpital intelligent (WHSN, Large-scale Wireless Hospital Sensor Network). Dans ce contexte, nous avons proposé le modèle UWBCAS pour assurer le partage des ressources spectrales entre les PANs. Puis, nous avons conçu et implémenté un protocole MAC multi-canal multi-créneau de temps avec support de qualité de service, PMCMTP, pour assurer une allocation conjointe des canaux de fréquence et des créneaux de temps au sein de chaque réseau PAN. Enfin nous avons proposé l’algorithme JSAR qui traite à la fois les problèmes d’ordonnancement des cycles d’activités des membres du réseau dans le but d’optimiser la consommation d’énergie, d’allocation efficace des canaux de fréquence et des créneaux de temps afin d’améliorer le taux d’utilisation des ressources et les performances du réseau et de routage avec support de QdS à critères multiples afin de répondre aux besoins des applications supportées